Localized corrosion, especially along the restoration margins, is a major cause of failure of amalgam restorations. Occluded corrosion cells set up in crevices and pores, and the environment inside them may differ considerably from the bulk. The corrosion attack may undermine the mechanical strength of the margins; in other cases the accumulation of corrosion products may stop the corrosion action and help to seal the restoration in the cavity. In the proposed work the environmental parameters inside artificial crevices in dental amalgam will be examined in vitro. Main attention will be paid to acidity and compositional variations in the crevices. Formation and composition of corrosion products in the crevice will be studied. The mechanism of localized corrosion will be investigated in special cells, simulating the electrochemical conditions in the occluded corrosion cells. Corrosion behavior of dental amalgam and its phases under conditions similar to those in the crevices will be examined by electrochemial and metallographical methods. Ways to improve the resistance to deterioration of amalgam restorations by localized corrosion will be sought. Composition and processing variables will be evaluated as regard to their effect on localized corrosion behavior.